1. ‫‪MICROBIOLOGY‬‬
‫‪for the Health Sciences‬‬
‫اعداد‬
‫أ. فريد ابو العمرين‬
‫ماجستير العلوم الطبية المخبرية‬
‫5 :‪CH‬‬
‫1‬

2. Chapter 5. Microbial Diversity
Part 2: Eucaryotic Microbes
• Introduction
• Fungi
• Algae
–
Characteristics
–
Characteristics and
–
Classification
Classification
–
Medical Significance
–
Medical Significance
• Protozoa
–
Characteristics
–
Classification and Medical
Significance
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• Lichens
• Slime Moulds

3. Algae
Characteristics and Classification
• Algae are photosynthetic, eucaryotic organisms.
• The study of algae is called phycology
• All algal cells consist of cytoplasm, a cell wall
(usually), a cell membrane, a nucleus, plastids,
ribosomes, mitochondria, and Golgi bodies.
• Algae range in size from unicellular microorganisms
to large, multi-cellular organisms.
• Algae produce energy by photosynthesis.
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4. Algae
• Algae may be arranged in colonies or strands and are found in
fresh and salt water, in wet soil, and on wet rocks.
• Most algal cell walls contain cellulose.
• Depending on their photosynthetic pigments, algae are
classified as green, golden, brown, or red algae.
• Algae include: diatoms, dinoflagellates, desmids, Spirogyra,
Chlamydomonas, Volvox, and Euglena.
• Algae are an important source of food, iodine, fertilizers,
emulsifiers, and stabilizers and gelling agents for jams and
culture media.
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5. Algae: Medical Significance
• Prototheca, is a very rare cause of human infections
• Causes protothecosis
• Prototheca lives in soil and can enter wounds, especially
those located on the feet.
•
It produces a small subcutaneous lesion that can
progress to a crusty, wartylooking lesion.
• Some Algae secrete toxic substances called phycotoxins
– Poisonous to humans, fish, and other animals
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6. Protozoa
Characteristics
• Protozoa are, eucaryotic organisms.
• Most protozoa are unicellular and free-living; found in soil
and water.
• Most protozoa are more animal-like than plant-like.
• All protozoal cells possess a variety of eucaryotic
structures/organelles.
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• Protozoa cannot make their own food; they ingest
whole algae, yeasts, bacteria, and smaller protozoa
for nutrients.

7. Protozoa
• Protozoa do-not have cell walls, but some possess a
thickened cell membrane called a “pellicle,” which
serves the same purpose – protection.
• A typical protozoan life cycle has 2 stages – a
trophozoite and a cyst.
 The trophozoite is the motile, feeding, dividing
stage.
 The cyst is the nonmotile, dormant, survival stage.
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8. Giardia
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9. Protozoa

Some protozoa are parasites.

Parasitic protozoa break down and absorb nutrients
from the body of the host in which they live.

Many parasitic protozoa are pathogens, such as
those that cause:
• Malaria,
• Giardiasis,
• African sleeping sickness,
• Amebic dysentery
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10. Classification and Medical Significance
of Protozoa
• Protozoa are divided into groups, based on their method of
locomotion:


Amebae move by means of pseudopodia (“false feet”).
One medically important ameba is Entamoeba
histolytica, which causes amebic dysentery (amebiasis)
and extraintestinal (meaning away from the intestine)
amebic abscesses.
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11. Medical Significance of Protozoa
 Ciliates move by means of hairlike
cilia – example: Balantidium coli,
the cause of balantidiasis.
 Causes dysentery in underdeveloped
countries.
 It is usually transmitted to humans
from drinking water.
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12. Medical Significance of Protozoa
 Flagellates move by means of whiplike
flagella.
 Pathogenic Flagellates:
• Trypanosoma brucei transmitted by the
tsetse fly, causes African sleeping sickness
in humans.
• Trichomonas vaginalis causes persistent
sexually transmitted infections
(trichomoniasis) of the male and female
genital tracts.
• Giardia lamblia causes a persistent
diarrheal disease (giardiasis).
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SEM of a Giardia lamblia trophozoite.

13. Medical Significance of Protozoa
• Sporozoa have no visible means of locomotion.
• Nonmotile protozoa
• The most important sporozoan pathogens:
• Plasmodium spp. that cause malaria.
• Malarial parasites are transmitted by female
Anopheles mosquitoes, which become infected
when they take a blood meal from a person with
malaria.
• Cryptosporidium parvum, causes severe diarrheal
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disease in immunosuppressed patients,
especially those with AIDS

14. Fungi
Characteristics
• The study of fungi is called mycology.
• Some fungi are harmful, some are beneficial.
 Beneficial fungi are important in the production of
cheeses, and other foods, as well as certain drugs
(e.g., the cyclosporine) and antibiotics (e.g.,
penicillin).
• Fungi represent a diverse group of eucaryotic
organisms that include yeasts, moulds, and
mushrooms.
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15. Fungi
• Fungal cell walls contain a polysaccharide called chitin.
 Many fungi are unicellular (e.g., yeasts), others grow as
filaments called hyphae which intertwine to form a mass
called a mycelium
• Some fungi have septate hyphae (the hyphae are divided
into cells by cross walls or septa).
• Some fungi have aseptate hyphae (the hyphae do not
have septa).
• Aseptate hyphae contain multinucleated cytoplasm.
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16. Fungal Colonies and Terms
Relating to Hyphae
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17. Fungi
Reproduction
•
Depending on the species, fungal cells can
reproduce by:
1. Budding,
2. Hyphal extension
3. The formation of spores.
–
There are 2 general categories of spores:
• Sexual spores
• Asexual spores
–
•
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Some fungi produce both asexual and sexual spores.
Fungal spores are very resistant structures.

18. Fungi
Classification
*
• Classification of fungi is based primarily on their
mode of sexual reproduction and the type of sexual
spore they produce.
• The 5 phyla of fungi are: Zygomycotina,
Chytridiomycotina, Ascomycotina, Basidiomycotina,
and Deuteromycotina.
• Deuteromycotina include the medically important
moulds such as Aspergillus and Penicillium.
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19. Microscopic Appearance
Aspergillus fumigatus
Penicillium sp.
Aspergilus flavus
Curvularia sp.
Scopulariopsis sp.
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*
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Histoplasma capsulatum

20. Yeasts
• Yeasts are eucaryotic, unicellular organisms that lack
mycelia.
• Yeasts usually reproduce by budding, but occasionally
by a type of spore formation.
• A string of elongated buds is known as a pseudohypha
(not really a hypha).
 Some yeasts (e.g., Candida albicans and Cryptococcus
neoformans) are human pathogens.
• Saccharomyces cerevisiae is a yeast used in baking.
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21. Fungi: Yeasts
• Yeast colonies may be difficult to distinguish
from bacterial colonies.
–
A simple wet mount can be used to differentiate
yeast colonies from bacterial colonies.
• Yeasts are larger than bacteria and are usually ovalshaped.
• Yeasts are often observed in the process of budding.
• Bacteria do not bud.
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22. Gram-Stained Clinical Specimen Containing
Yeasts, Bacteria, and White Blood Cells
Yeasts
Bacteria
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23. Fungi: Moulds
• Moulds are often seen in water and soil and growing on food.
• Moulds produce cytoplasmic filaments called hyphae.
– Aerial hyphae extend above the surface of whatever the
mould is growing on.
–
Vegetative hyphae grow beneath the surface.
• Reproduction is by spore formation, either sexually or
asexually, on the aerial hyphae (also known as reproductive
hyphae).
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24. Fungi: Moulds
• Moulds have great commercial importance.
– Some produce antibiotics.
• Examples: Penicillium and Cephalosporium
–
Some moulds are used to produce large quantities of
enzymes that are used commercially.
–
The flavor of cheeses like bleu cheese, Roquefort,
camembert, and limburger are due to moulds that
grow in them.
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25. Fungi: Fleshy Fungi
• Include mushrooms, toadstools, puffballs and
bracket fungi
• Consist of a network of filaments or strands (the
mycelium) that grows in soil or on rotting logs
• The fruiting body that grows above the ground forms
and releases spores
• Some mushrooms are edible; some are extremely
toxic.
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26. Fungi
Medical Significance
•
A variety of fungi including yeasts, moulds, and some fleshy
fungi, are of medical, veterinary and agricultural importance
because of the diseases they cause in humans, animals, and
plants.
•
The infectious diseases of humans and animals that are
caused by moulds are called mycoses.
•
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Fungal infections of humans are categorized as:
1.
2.
3.
4.
Superficial
Cutaneous
Subcutaneous
Systemic mycoses.

27. Superficial and Cutaneous Mycoses
• Superficial mycoses are fungal infections of the outermost
areas of the human body – hair, nails and epidermis.
• Cutaneous mycoses are fungal infections of the living layer
of the skin, the dermis.
–
A group of moulds collectively referred to as
dermatophytes cause tinea (“ringworm”) infections.
–
The yeast, Candida albicans, can also cause cutaneous,
oral, and vaginal infections.
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28. Subcutaneous and Systemic Mycoses
• Subcutaneous and systemic mycoses are more
severe types of fungal infections.
• Subcutaneous mycoses are fungal infections of the
dermis and underlying tissues.
• Systemic mycoses are fungal infections of the
internal organs of the body.
–
Spores of some pathogenic fungi may be inhaled with dust
from contaminated soil or dried bird or bat feces. They
may also enter through wounds of the hands and feet.
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29. Subcutaneous and Systemic Mycoses
• Examples of deep-seated pulmonary infections include:
•
•
•
•
Blastomycosis
Coccidioidomycosis
Cryptococcosis
Histoplasmosis.
• Inhalation of common bread moulds like Rhizopus and Mucor
spp. can cause disease and even death in immunosuppressed
patients.
• Diagnosis of mycoses is accomplished by culture techniques
and immunodiagnostic procedures.
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30. Dimorphic Fungi
• A few fungi, including some pathogens, can live as
either yeasts or moulds, depending on growth
conditions.
• This phenomenon is known as dimorphism and the
fungi are called dimorphic fungi.
–
–
When grown in vitro at room temperature (25oC), dimorphic
fungi exist as moulds, producing mould colonies.
–
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When grown in vitro at body temperature (37oC), dimorphic
fungi grow as yeasts and produce yeast colonies.
In vivo, dimorphic fungi exist as yeasts.

31. Dimorphic Fungi
• Dimorphic fungi that cause
human diseases include:
–
Histoplasma capsulatum
(histoplasmosis)
–
Sporothrix schenckii
(sporotrichosis)
–
Coccidioides immitis
(coccidioidomycosis)
–
Blastomyces dermatitidis
(blastomycosis)
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32. Lichens and Slime Moulds
• Lichens are observed as colored, often circular
patches on tree trunks and rocks.
• Slime moulds are found in soil and on rotting logs.
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33. Different Types of Lichens
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